It is known to package products, including food products, in a wrapper that is fabricated from a substantially gas and moisture impervious material, such as a metal foil, or a plastics material (including a laminate of either or both materials), in order to protect the product.
Such known wrappers may be formed from a length of flat, foldable material having an inner surface directed to the product and an outer surface. The outer surface may be printed on or otherwise be provided with information for the consumer. The material is folded about the product and the longitudinal side edges are bonded together to form a longitudinal sealed seam, sometimes referred to as a “fin seal” or “fin seam”. The material extends beyond the ends of the product and opposing edge regions at either end of the wrapper are bonded together to form transverse end seams. The seams may be formed using an adhesive to bond the opposing surfaces of the wrapper or by heating the material under pressure so that the opposing surfaces melt and fuse together to form a welded seam.
Packaging of this nature can be produced using a flow-wrap method in which a film of material is supplied in a roll to package a number of products in a substantially continuous process. The material is fed through a machine which folds it about each product in turn so that opposing side edges are brought into contact and bonded together to form the longitudinal seam, which usually extends along a rear face of the product. The material is crimped at either end of the product to form the end seams and the material is cut to separate each package from the remainder of the film.
FIG. 1 shows a commonly used laminated film 10 used in a flow-wrap method. The laminated film comprises an outer surface 11 formed of a clear oriented polypropylene (OPP) 12, to which an image formed from a layer of ink 14 is reverse printed. The reverse printed OPP 12 is adhered, by means of an adhesive 16 to a metallic foil layer 18—this foil layer providing the material with a reflective metallic coloured finish. The metallic foil layer in turn has been applied to a substrate of white OPP 20 by means of vacuum or vapour deposition. The non-metallic coated surface of the white OPP 20 forms the inner surface 13 of the laminated material. Once formed, the laminated material 10 can be made into the packaging and sealed at the edges with a permanent adhesive.
A number of laminated packaging materials incorporating resealable flaps are known in the art. For example, EP1449789 discloses a packaging container comprising a packing film which is formed from a laminated material incorporating perforations or cut lines on the outer and inner surfaces of the laminated film which may be produced by means of mechanical knives or lasers.
FIG. 2A shows a known laminated film 50 which includes a resealable flap, where the outer and inner surfaces (these surfaces being generally denoted 52 & 54 respectively) are cut in an offset manner by means of lasers. Briefly, the laminated film in FIG. 2A comprises a layer of white OPP 56, to which is applied an image formed a layer of ink 58. Overlaying the layer of ink 58 is a layer of clear varnish 60 to protect the image during handling of the laminated film. To the underside of the white OPP 56, an upper metallic foil layer 62 has been applied by means of vacuum or vapour deposition. The upper metallic foil layer 62 is adhered to a lower foil layer 64 by means of a layer of resealable adhesive 66. The lower foil layer has in turn been deposited on a further layer of white OPP 68. Lasers 70 and 72 located above and below the laminate 50 can make offset score lines in the upper 52 and lower 54 portions of the laminate so that a resealable flap can be produced (as illustrated in FIG. 2B). Generally speaking, the foil layers 62 and 64 are intended to be cut and also prevent the lasers from passing any further in the material during the cutting step. However, in practice, each of the foil layers tends to only attenuate the cutting power of the laser and the following foil layer actually stops the laser from penetrating the laminate any further. This is schematically shown in FIG. 2A by the path of the laser penetrating the laminate up to the first foil layer it encounters with a solid line and thereafter a dotted line after is has been attenuated and that the second foil layer actually prevents any further penetration. FIG. 2B shows the laminate after being cut by the laser and has an upper cut 74 extending from the varnish 60 to the lower metallic foil layer 64 and a lower cut 76 extending from the further layer of white OPP 68 to the upper metallic foil layer 62. Unfortunately, the laminate material illustrated in FIGS. 2A and 2B is quite thick resulting in handling and wrapping problems and having more than one foil layer greatly increases the cost of the material.
It is an object of the present invention to overcome one or more problems associated with the prior art laminated materials. It is also an object to produce an inexpensive laminated material having offset cuts above and below the material which can be produced using a laser. A further object of the present invention is to provide a laminated material which can be reverse printed to improve quality of the finished product and overcome the requirement of a surface varnish.